The treatment of human skin with various agents has been undertaken for many years with the goal being to keep the skin in a smooth and supple condition. Skin has the tendency to dry out when exposed to conditions of low humidity or to detergent solutions for extended periods. Skin is made up of several layers of cells which coat and protect the keratin and collagen fibrous proteins that form the skeleton of its structure. The outermost of these layer, referred to as the stratum corneum, is known to be composed of 250 A protein bundles surrounded by 80 A thick layers. Anionic surfactants and organic solvents typically penetrate the stratum corneum membrane and, by delipidization (i.e. removal of the lipids from the stratum corneum), destroy its integrity. This destruction of the skin surface topography leads to a rough feel and may eventually permit the surfactant or solvent to interact with the keratin, creating irritation.
It is now recognized that maintaining the proper water gradient across the stratum corneum is important to its functionality. Most of this water, which is sometimes considered to be the stratum corneum's plasticizer, comes from inside the body. If the humidity is too low, such as in a cold climate, insufficient water remains in the outer layers of the stratum corneum to properly plasticize the tissue; and the skin begins to scale and becomes itchy. Skin permeability is also decreased somewhat when there is inadequate water across the stratum corneum. On the other hand, too much water on the outside of the skin causes the stratum corneum to ultimately absorb three to five times its own weight of bound water. This swells and puckers the skin and results in approximately a two to three fold increase in the permeability of the skin to water and other polar molecules.
Thus, a need exists for compositions which will assist the facial stratum corneum in maintaining the optimum performance of its barrier and water retention functions, in spite of deleterious interactions which the skin may encounter in washing, work, and recreation.
Conventional cosmetic cream and lotion compositions as described, for example, in Sagarin, Cosmetics Science and Technology, 2nd Edition, Volume 1, Wiley Interscience (1972) and Encyclopedia of Chemical Technology, Third Edition, Volume 7 are known to provide varying degrees of emolliency, barrier and water-retention (moisturizing) benefits. However, they can also suffer serious negatives in terms of skin feel (i.e. they often feel very greasy on the skin) as well as having poor rub-in, absorption and residue characteristics. Other cosmetic compositions are disclosed in, for example, U.S. Pat. No. 4,837,019 to Georgalas et al., issued Jun. 16, 1989 and also in U.S. Pat. No. 4,863,725 to Deckner et al., issued Sep. 5, 1989, both of which are incorporated by reference herein.
To improve moisturizing benefits water-soluble humectants such as glycerine have been added to cosmetic compositions; however these water-soluble humectants generally significantly increase the tacky feeling. Applicants have found that the use of a specific silicone component in substantially oil-free aqueous gel-type compositions provides significantly improved skin feel and provides a visually appealing product. Further, these compositions, when applied to the skin, provide the user with improved make-up application and protection from environmental factors (e.g., irritants such as wind, heat and cold) as well as protection from common household irritants (e.g., cleansers and the like). These substantially oil-free gel-type cosmetic compositions are also particularly useful in warmer climates because they reduce the tack associated with heat and humidity.
The present invention therefore provides substantially oil-free gel-type cosmetic compositions which provide improvements in absorption, residue and skinfeel characteristics without detriment to either short or longer term moisturizing effectiveness or emolliency.
It is therefore an object of the present invention to provide improved facial compositions which provide reduced tack and provide the user with a smoother skin feel. It is a further object of the present invention to provide oil-free moisturization to minimize skin regreasing over time. It is still a further object to provide skin care compositions which, when applied, provide improved make-up application as well as improved protection from environmental and common household irritants.
These and other objects of this invention will become apparent in light of the following disclosure.